Observe the relationship between first two words and then fill the suitable word/words at the fourth place.
Osmotic pressure : Osmotic potential :: DPD : ......................

Explanation

To solve the analogy "Osmotic pressure : Osmotic potential :: DPD : ?", we need to analyze the relationship between the first two terms and apply the same logic to find the fourth term.

### Step-by-Step Solution:

1. **Understanding the First Pair**:
- Osmotic pressure and osmotic potential are related concepts in plant physiology.
- Osmotic pressure refers to the pressure required to prevent the flow of water into a solution via osmosis, and it is always a positive value.
- Osmotic potential, on the other hand, is the potential energy of water in a solution and is usually expressed as a negative value.
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